Electrolytic deposition of metals



Sept. 28 1926.

M. M. MERRITT ELECTROLYTIC DEPOSITION A OF METALS Filed August 20, 1925 2 Sheets-Shes*v sept. 2s, 192e.` 1,601,693

M. M. MERRITT ELECTROLYTIC DEPOSITION OF METALS Filed August 20, 1925 2 Smeets-sheet 2 Patented Sept. 28, 1926.

UNITED STATES MATTHEW M. MERRITT, OF MIDDLETON, MASSACHUSETTS, ASSIGNOR TO INDUSTRIAL DEVELOPMENT CORPORATION, OF PORTLAND, MAINE, A CORPORATION OF MAINE.

ELECTROLYTIC DEPOSITION 0F METALS.

Application led August 20, 1925.- Serial No.' 51,380.

My invention pertains to improvements in electrolytic methods and apparatus, and particularly but not exclusivelyto methods of and apparatus for making sheet metal by electrodeposition.

My invention will be best Vunderstood from the following description when read in the light of the accompanying drawings of` one specific embodiment of my invention selected for illustrative purposes, while the scope of my invention will be more particularly pointed out in the appended claims.

In the drawings 'z Fig. 1 shows a plan of apparatus arranged according to my invention;

Fig. 2 is a section on the 1, and in addition showsmore or less diagrammatically on an enlarged scale mecha.- nism for automatically controlling the steam su ply to the heater; and

1g. 3 is a section on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary section on an enlarged scale through the right hand end of the drum having the cathode, and associated parts,'on `the line 2-2 of Fig. 1; and

Fig. 5 is a s ection on the line 5-5 of Fig. 1.

Referringto the -drawings have shown a cylindrical drum l provided with frusto- .conical or taperedends 3, the drum being formed ofwood, porcelain, or other suitable non-conducting material and carrying intermediate its length an endless sheet 5 of cooper or othersuitable conducting material constituting a cathode upon which the metal sheet to be formed is deposited from the electrolyte. The length of the cathode corresponds tothe width ofthe deposited sheet illustrated at v7. As the sheet is deposited on the cathode it is stripped therefrom by a rotating ,drumy 9, thesurface of the cathode being treated with mercury to form thereon a thin coating 10 of amalgam for facilitating the stripping operation. For further facilitating'the stripping operation and for giving the` sheet a properly formed edge the'cathode abuts at. each end with the ring 11 of rubber or other suitable nonconducting material carried by the drum.

For rotating the drums 1 and 9 in order toA strip the deposited sheet fromthe former une 2-2 of Fig.

and wind it upon the latter the same are respectively carried by shafts 12 and 13 which are conjointly rotated by suitable mechanism not necessary to describe herein. The drum is'in contact conveniently to a depth of approximately one-third its diameter with a `swift-flowing continuous stream of electrolyte the level of which is indicated at 15 in Fig. 2. The electrolyte flows past the drum i a trough 17'having a lininglS of lead or other suitable conducting material insoluble in the electrolyte, the lining constituting an .anode the surface of which is uniformlyV distributed in relatively close proximity to the surface of the cathode 5.

The level of the electrolyte in the trough is maintained substantially horizontal, that is@ to say parallel with the axis of the drum by means of an adjustable dam 19 having a lower opening 21 through which the major portion of the electrolyte discharges from the trough, the remaining small portion of the electrolyte flowing over the dam through notch 22 formed on the upper edge of the The electrolyte leaving the,trough 17 discharges into a trough 23 leaving the latter through a pipe 25 in communication with a pump 27. The pump 27 forces the electrolyte through a pipe 29 into a,heater 31,

the electrolyte after being heated leaving as a tower 34 containing a body 35 of soluble metal bearing material for replenishing the metal content lor' the electrolyte. This soluble material may be in any suitable form, as for example ore, suitable metal salts or metal scrap, preferably the latter.

The electrolyte discharges, to the lower end of the towery through orifices 37 into a downwardly inclined chute 39 which conducts the elctrolyte into, a distributing trough 41, the latter communicating with any desired number of troughs 17, onl one of whichhas been illustrated in the rawings. For giving the electrolyte considerable velocity as it passes through the troughs 17 between the@ conductors constituting the cathode and the anode the chute connecting the trough A41 with the trough 17 at its bottom is constructed in the formof an apron 43. The amount of electrolyte entering each trough 17 if a plurality o f troughs 17 are provided, iscontrolled by suitable gates 45.

Conveniently I provide means for regulating the ratio of amount of electrolyte to amount of surface of-the metal bearing material on which the electrolyte acts, and for this purpose preferably provide means for regulating the amount of electrolyte passing through the replenishing material in the tower. To this end I .have herein illustrated means for by-passing a portion of the electrolyte around the tower, providing for the purpose a branch pipe 47 in communication with the pipe 33 and discharging into a funnel 49 which at its lower end discharges into the inlet end of the chute 39. 'The chute 39 is provided ,with baliles 51 for thoroughly mixing the stream of electrolyte discharging from the tower with that discharging from the funnel 49, and for regulating the effective cross-sectional area of the pipe 47 and thus the amount of electrolyte passing through the pipe I provide the same with a suitable gate valve 50.

The heater as herein illustrated comprises a shell 53 having upper and lower headers 55 dividing the heater into upper and lower steam chambers 57 and a central or elect-rolyte chamber 59. The steam is supplied the upper steam chamber 57 through a pipe 61 and passes through tubes 63 to the lower steam chamber 57, the condensed steam discharging from the lower steam chamber through a pipe 65. lAs will be obvious the exteriors of the tubes 63 constitute the heating surface of the heater. n

In practice the negative terminal of a battery lor' other source of direct current electromotive force is connected-to the cathode by means herein conveniently illustrated as a brush 69 in contact with a slip ring 71 carried by the shaft 12 in electrical communication therewith, the shaft being placed in electrical communication with the cathodel by means of a conductor 73 (Fig. 5). The

positive pole of the battery 67 is connected to the insoluble lining 18 of the trough, as for example byl means of a terminal (not shown herein) running the length of that portion of the lining opposite the cathode 5. It will be observed that with the battery connected t-o the cathode and anode as above described the metal bearing material 35 in the tower 34 will be maintained at the same electrical potential as the lining 18 of the trough by reason of the fact that the circulating electrolyte constitutes a conductor placing the two in electrical communication. I have found that by thus impressing sutlicient potential on the metal bearing material them'etal of the same will enter into the solution in the electrolyte which enables me to replace in 'the electrolyte the metal deplenishing the metal content of the 'electrolyte I preferably use sheet metal scrap in the tower 34. I have found when using an insoluble anode that satisfactory results can be obtained when a positive electrical potential of notless than 11/2 volts is impressed on the copper scrap, although a much lower voltage can be employed when a soluble anode is used.

For a given temperature of electrolyte apparentlv the rate of replenishment of the electrolyte effected in a given time by the impressed voltage is directly dependent upon both the Aamount of electrolyte and the amount of surface of soluble metal bearing material in contact with which the electrolyte flows. For a given ratio of amount of electrolyte to amount of surface of metal bearing material upon which the electrolyte acts in a given time the rate of replenishment of the metal content of the electrolyte is a direct function of the temperature of the electrolyte. To obtain the best results I have found that the metal content of the electrolyte should not be above a certain maximum value or below a certain minimum value, and accordingly that the best results can be obtained by controlling the rate of replenishment in such manner that the metal content will bemaintained within these limits so as to effect an average rate of replenishment approximating the rate of deposition of metal from the electrolyte upon the cathode.

In practice I preferably proportion the rationof am'ount of surface of metal bearing material in the tower to amount of electrolyte acting upon the metal bearing material so that under normal temperatures the rate of replenishment of metal content of the electrolyte will be slower than the rate` of deposition of metal from the electrolyte upon the cathode. I may obtain` this ratio if all the electrolyte passes through the tower by placing in the tower an amount of electrolyte necessary to obtain the des'red ratio, but preferably I obtain the ratio by adjusting the valve 50 inthe pipe 47 to permit a requisite amount ofthe electrolyte to be bypassed around the tower through the pipe 47 and funnel 49.- In order to obtain a rate of replenishment of the metal content ofthe electrolyte sulficient to replace in the electrolyte the metal -deposited on the cathode I raise the temperature of the electrolyte to sults can be obtained by operating the heater at a relatively high temperature sufficient to\eii'ect a rate of replenishment greater than the rate of deposition and continuing the operation at this relatively high temperature until the metal content of the electrolyte rises to a maximum limit of satisfactory operation whereupon then operating the heater at a lower temperature suicient to effect a rate of replenishment slower than' the rate of deposition and continuing the operation ofthe heater 'at this lower temperature until\the metal content of the electrolyte reachesthe ,lower limit at which sat' isfactory results can be obtained, whereupon then rai's'ng the temperature to the higher temperature again to increase the rate of re-` plenishment., By thus alternately raising and lowering the temperature of the electrolyte to maintain the metal content between upper and lower limits an averagerate of replenishmentcan beeffected equal to the rate of deposition. In practice I have found that'satisfactory results can be obtained when the upper limit of metal con-` tent of the electrolyte corresponds to 32 ounces of copper sulphate crystals per gallon of electrolyte, and the lower limit of metal content corresponds to 26 ounces of copper sulphate crystals per gallon, the sulphuric acid concentration at these limits being respectively 6 and 10 per cent, and these l limits of metal and acid content corresponding respectively to electrolyte specific gravities of 1.24 and 1.18.' I have found that satisfactory results can be obtained by operating the heater at approximately 165 degrees Fahrenheit for obtaining the maximum limit 'of metal content and 120 degrees Fahrenheit for obtaining the lower limit of metal content. It will be understood that if higher and lower temperatures than those stated are employed the rate of replenishment will be correspondingly increased and diminished. v

For controlling the metal content of the electrolyte automatically I have shown a float or hydrometer for controlling the steam supply to the heater. It will be understood that the float 75 will rise and fall in accordance with the specilic gravity of the electrolyte which is a direct function of lits metal content. As illustrated the float.is situated at the discharge end of the chute 39 and is surrounded bya screen 77 of lead or other material insoluble'in the electrolyte for breaking the force of the current directed against the float.

Referring particularly to Fig. 5 the float 75 is provided with a stem 79 .which carries a block of insulating material 8l. supporting a contact ring 83, the block of insulating material being carried by a rod l85 screw 'threaded into the end of the stem 79 so that the distance between the float and the contact Lrin can be varied by rotating the rod 85 relat1vely to the stem 79. Cooperating with the contact ring 85 are spring contacts 87 and 89. It will be understood that when the float rises due to'an L,increase in speciic gravity to the maximum desired working limit o'f metal content the contact ring 83 will contact the spring contact 87, and that when the float falls due to a decrease in speciic gravity to the lower limit the contact ring will contact the spring contact 89.

The ring contact 83 is connected by means of conductors 91 and 93 with one terminal of a battery 95 (Fig. 2), the other terminal of the battery being connected in multiple to one end of each of a pair of solenoid coils 97 and 99, the opposite end of the coil 97 being connected by means of a conductor 101 with the spring contact 89 and the opposite end of the coil 99 being connected by means of a conductor 103 with the spring contact 87. In operative relation to the solenoid coils 97 and 99 are armatures 105 and 107 carried by a rod 109 of non-magnetic material for actuatin a pilot'valve 111 controlling a main va ve 113 for the steamv supply to the heater.

The stem 115 of the controlling valve '113 is connected to a iexible diaphragm 117 and to one end of a lever 119, the latter being pivotally supported at 121 and having its opposite end bearing against a compression spring 123. It will be observed that if a pressure fluid is admitted to the closed chamberv 125 below the diaphragm the valve stem 115 will be pressed upwardly as viewed in Fig. 2, and that if the chamber 125 is connected to the atmosphere to relieve it of pressure the spring 123 will return the valve stem to theposition shown in the drawings. The controlling valve 113 is s o arranged that when the diaphragm chamber 125 is exhausted the controlling largement 131 connected by means of a pipel 133 with the diaphragm chamber 125 so that in the position shown by the drawings the diaphragm chamber will be connected lto the atmosphere. At an intermediate portion the bore 127 is provided with an annular enlargement 135 connected by means of a pipe 137 with the steam pipe 61. The valve is provided with an annular reduced portion 139 which when the valve is movedto the right hand end of the bore 127 will lll place the enlargement 135 in communication with the enlargement 131, and in consequence place the diaphragm chamber 135 in communication with the steam pipe 61.

Assuming the float is in the position shown by Figs. 2 and 5 and the specific gravity yof the electrolyte falls suciently to cause the ioat to descend far enough to bring the contact ring in contact with the spring Contact 89, this will energize the solenoid coil 97 and cause the armature 105 yto be drawn into the'coil which will shift the valve to the right hand end of its travel and place the pipe 137 in communication with the enlargement 135, thus allow' ing steam to enter the diaphragm chamber 125 and force the Valve stem 115 upwardly to open the controlling valve 113 and supply steam to the heater. Now if the specific gravity of the electrolyte rises sufliciently to cause the float to place the contact ring 83 into contact with the spring contact 87 the solenoid coil 99 will be energized to effect movement of the valve into the position shown by Fig. 2 which will cause the diaphragm chamber 125 to be exhausted, thus permitting the spring 123 .to move the Valve stem 115 downwardly and close the valve 113.

For aording a by-pass around the controlling valve 113 so as to allow steam toenter the heater when the valve 113 is closed I provide a by-pass pipe 141 controlled by a valve 143.A As is obvious the valve 143 may be opened sufcientlylto permit enough steam to enter the heater for maintaining the temperature of the electrolyte at any desired lower limit, the temperature rising due to the increased amount of steam entering the heater when the Valve 113 opens.

Also if desired I provide the steam pipe 61 v with an adjustable pressure reducing valve 145, thus affording means for controlling the pressure of the steam s upplied thev heater.

When it is desired to control the metal content of the electrolyte manually by means of the heater Irclosethe. valve' 147 in the pipe 137 so as to interrupt the supply of steam to the valve 111, open fully the valve 143 and control the amount of steam entering the heater by manipulating the valve 147 in the steam pipe 61.

Although I have described for purposes of illustration one specific embodiment of apparatus constructed and arranged according to my invention and one specific way of performing my method it is to be understood that I am not limited thereby to their particular details and to the specific values herein given, but that within the scope ot my invention Wide deviations may be made therefrom wthoutdeparting from the spirit of my invention.

Claims:

l. That method of replenishing the metal content of an electrolyte after depletion of the metal content by electrolytic deposition which comprises allowing the electrolyte to act on metal-bearing material while regulating the rate at which metal is dissolved by ontrolling the temperature of the electroyte. i.

2. That method of replenishing the metal content of an electrolyte after depletion of the metal content by electrolytic deposition which comprises allowing the electrolyte to act on metal-bearing material on which is impressed an electrical potential while regulating the rate at which metal is dissolved by controlling the temperature of the electrolyte.

3. That electrolytic method which comprises depositing metal from a circulating electrolyte swiftly flowing between conductors constituting a cathode and an anode, and replenishiug the metal content of the electrolyte while heating the electrolyte and allowing it while circulating to act on soluble metal-bearing material on which is impressed an electrical potential.

4. That electrolytic. method which comprises depositing metal from a circulating electrolyte swiftly flowing between conductors constituting a cathode and an insoluble anode, and replenishing the metal content of the electrolyte while heating the electrolyte and allowing it while circulating to act on soluble vmetal-bearing material on which is impressed an electrical potential.

5. 'Ihat electrolytic method which coniprises circulating tlie electrolyte between the opposed surfaces ofconductors one of which constitutes a. cathode and the other an anode insoluble in the electrolyte, replenishing the electrolyte by allowing it while circulating to act on soluble metal-bearing materialen which is impressed an electrical potential, and regulating the rate of replenishment by controlling the temperature of the electrol te.

Y6. That electrolytic method which coinprises depositing met'al from a circulating electrolyte on a cathode, effecting solution of metal in the electrolyte by allowing the electrolyte while circulating to act on soluble nietal-bearing material on which is mpressed anelect-rical potential, the amount of soluble material on which the electrolyte acts being insufficient to effect at normal temperatures a rate of replenishment of metal-content of the electrolyte as great as the rate of deposition of metal on the cathode, and increasing the rate of replenishment by yheating the electrolyte.

7. That electrolytic method which comprises depositing metal from a circulating electrolyte on a cathode, replenishing the metal-content of the `electrolyte by allowing it to act while circulating on soluble metal- 'bearing material on which is impressed an electrical potentlal, and eilectlng an average ratel of replenishment of. the metal-content of the electrolyte equal to the rate of depositionv ofmetalo'n the cathode by alternately effecting an increase and decrease in the temperature ot the'electr'olyte. f

8. That electrolyticfmethod` which .com- .prises depositing metaltfrom "a circulating electrolyte on a cathode,.eiecting solution of metal in the electrolyte'bylflallowing.the electrolyte while v circulatingto. act `onfsoluble A metal-bearing material' onfwhichA is impressed anv electrical potential, -theamount of soluble material relative to`the-ffamount ofelectrolyte actingthereon being such as to e'ect at normal temperaturesagratefof replenishment of the metal-content jof the Velectrolyte ,differentfrom the rate of vdeposition v of metal on the cathode, and effecting a resultant rate of Y replenishment equal tothe rate of deposition'by changing the temperature of the electrolyte vfromnormal temper'-` ature.

9. That electrolytic method which comprises circulating the electrolyte between the opposed surfaces of conductors one of which constitutes a cathode and the other an anode insoluble in the electrolyte, replenishing the equal to' the rate yof deposition by raising the temperature of the electrolyte above normal temperature.

10. That electrolytic method which comprises circulating the electrolyte between the opposed surfaces of conductors one of which constitutes a cathode and the other an anode insoluble in the electlyte, replenishing the electrolyte by allowing it while circulating to act on soluble metal-bearing material on which is impressed an electrical potential, the amount of soluble material relative to the amount of electrolyte acting thereon being such as to effect at normal temperatures a rate of replenishment less than the rate of deposition of metal on the'cathode, and effecting an average rate of replenishment of the metal content of the electrolyte equal to the rate of deposition by alternately eii'ecting an increase and decrease in the temperature of the electrolyte.

11. That electrolytic method'which comprises depositing metal from'y a circulating electrolyte on a cathode, effecting solution of metalin the electrolyte by allowing the elec'- trolyte while circulating to act on soluble metal-bearing material on which is impressed an electrical potential, the amount of soluble material on which the electrolyte acts being insuiiicient to effect at normal temperatures a rate of @replenishment of metal-content of the electrolyte as great as the rate of deposition of metal on. the cathode, increasing the temperature of the electrolyte sufficiently to effect a rate of replenishment greater than the rate of deposition when the metal content of the electrolyte decreases to a desired lower limit, and diminishing the temperature of the electrolyte suiliciently to effect a rate of replenishment less than the rate of deposition when the .metal-content of the electrolyte increases to a desired upper limit.

12. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathodeand the other an anode, a container for soluble metal-bearing `materlal for replenishing the electrolyte,

means .for circulating the electrolyte for l"eiecting flow thereof swiftly between said opposed conductors and inV contact with said material, and means for heating the electrolyte for accelerating its action on said material.

13. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and-the other of which is insoluble in the electrolyte and constitutes an anode, soluble metal-bearingmateria-l for replenishing the electrolyte, means -for circulatlng the electrolyte for effecting flow thereof between said opposed conductors and in contact with said material, and

means ,for heating the electrolyte for accelerating its action on said material.

14. Electrolytic apparatus comprising in combination, opposed conductors one y0i" which constitutes a cathode and the .other an anode, a container for soluble metal-bearing material for replenishing the electrolyte, means for circulating 'the electrolyte for effecting flow thereof between said opposed conductors in a swift stream and in contact with said material, and means for heating the'electrolyte for accelerating its action on said material.

15. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, la container for soluble metal-bearing` material for replenishing the electrolyte, means for circulating the electrolyte forv effecting flow thereof between said opposed conductors in a swift stream and in contact with said material, and means f or heating the electrolyte for accelerating lts -action on said material.

' 16. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other an anode, a container for soluble metal-bearing,

material for replenishing the electrolyte, means for circulating the electrolyte for elfecting low'thereof between said opposed conductors and in contact with said material, means for varying the ratio of the amount of electrolyte to the amount of said material acted upon by the electrolyte, and means for heating the electrolyte for accelerating its action on said material.

17. Electrolyti'c apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, soluble metal-bearing material for replenishing the electrolyte, means for circulating the electrolyte for effecting flow thereof between said opposed conductors and in Contact with said material, means for varying the ratio of the amount of electrolyte to the amount of said material acted upon by the electrolyte, and means for heating the electrolyte for accelerating its action on said material.

1,8. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other an anode, soluble metal-bearing material for replenishing the electrolyte, means for circulating the electrolyte for effecting flow thereof between said opposed conductors in a swift stream and in Contact with said material, means for Varying the ratio of the amount of electrolyte to the amount of said material acted upon by the electrolyte, and means for heating the electrolyte for accelerating its action on said material.

19. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, soluble metal-bearing material for replenishing the electrolyte, means for circulating the electrolyte for effecting flow thereof between said opposed conductors in a swift stream and in contact with said material, means for varying the ratio of the amount of electrolyte to the amount of said material acted upon by the electrolyte, and means for heating the electrolyte for accelerating its actionxon said material.

20. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other an anode, soluble metal-bearing material for replenishing the electrolyte, means for circulating the electrolyte for effecting flow thereof between'said opposed conductors and in contact with said material, and means for raising and lowering the temperatureof the electrolyte for effecting acceleration and retardation of its action on said material.

21. Electrolytic apparatus comprising in Leonesa combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode,'soluble metal-bearing material for replenishing the electrolyte,l means for circulating the electrolyte for effecting flow thereof between said opposed conductors and in contact with said material and means for raising and lowering the tem-V perature of the electrolyte for effecting acu celeration and retardation of its action on said material.

22. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, soluble metal-bearing material for replenishing the electrolyte, means for circulating the electrolyte for effecting flow thereof inal swift stream between said opposed conductors and in contact with said material, and means fortraising and lowering the temperature of the electrolyte for effecting acceleration and retardation of its action on said material.

23. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other an anode, a heater for the electrolyte, a container for a body of soluble metal-bearing material for replenishing the electrolyte, and means for circulating the electrolyte includ- .ing means for guiding it between said 0pposed conductors and passing it through said heater and said body.

24C. Electrolytic ap aratus comprising in combination, oppose conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, a heater for the electrolyte, a container for a body of soluble metal-bearing material for replenishing the electrolyte, and means for circulating the electrolyte including means for guiding it between said opposed conductors and passing it through said heater and said body.

25. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other an anode, a heater for the electrolyte, a container for a body of soluble metal-bearing material for replenishing the electrolyte, and means for circulating the electrolyte including means for guiding it between said opposed conductors in a swift-flowing stream and passing it through said heater and said body.

26. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, a heater for the electrolyte, a body of soluble metal-bearing material for replenishing the electrolyte, and means for circulating the electrolyte between said opposed conductors in a swiftlowing stream and through said heater and `said body. l.

anode, a heater for the electrolyte, soluble metal-bearing material for the electrolyte, means for circulating the electrolyte between said opposed conductors and through said heater and said body, and means for varying the ratio of the amount of electrolyte to the amount of said material acted upon by the electrolyte.

28. Electrolytic apparatus comprising in combination, opposed conductors one of which constitutes a cathode and the other of which is insoluble in the electrolyte and constitutes an anode, a heater for the electrolyte, soluble metal-bearing material for the electrolyte, means for circulating the electrolyte between said opposed conductors and through said heater and said body, and means for Varying the ratio of the amount of electrolyte to the amount of said material acted upon by the electrolyte.

29. Electrolytic apparatus comprising in combination, a cathode for deposition thereon of metal from the electrolyte, means for replenishing the metal-content of the electrolyte comprising soluble metal-bearing material in contact with the electrolyte, and means for automatically changing the temperature of the electrolyte in response to changes in specific gravity of the electrolyte for controlling the rate ot' replenishment.

80. Electrolytic apparatus comprising in lacombination, opposed conductors constituting a cathode and an anode, soluble metalbearing material for replenishing the electrolyte, means for circulating the electrolyte between said opposed conductors and in contact with said material, heating means for the electrolyte, and means for controlling said heating means automatically in response to changes in specific gravity of the electrolyte for varying the temperature of the electrolyte to effect control of the rate of replenishment.

In testimony whereof, I have signed my name to this specification.

MATTHEW M. MERRITT. 

